1. Field of the Invention
The present invention relates generally to wafer holders for semiconductor manufacturing apparatus and semiconductor manufacturing apparatus using the same and particularly to wafer holders for semiconductor manufacturing apparatus having a heater for heating a wafer, an electrode for an electrostatic chuck electrostatically holding a wafer or the functions of both of such heater and electrode, and semiconductor manufacturing apparatus using the same.
2. Description of the Background Art
In etching a surface of a semiconductor wafer or depositing a film thereon, a multitude of such wafers are held on a rack and batch-processed, exposed to an etchant gas or a gas for deposition, and circumferentially heated with a heater, as required. This technique is referred to as hot-wall technique.
In recent years, however, as semiconductor is required to be more highly integrated and operate more rapidly, semiconductor manufacturing apparatus have therein uneven temperature and gas flow varying with different portions thereof and such unevenness in temperature and gas flow disadvantageously varies the quality of a film etched or deposited. Accordingly, the batch process as described above is being replaced by arranging multiple etching apparatus and deposition apparatus and using a loader therebetween to automatically feed wafers to process a single wafer at one time. In doing so, the loader transfers a wafer to an etching apparatus or a deposition apparatus and places the wafer in a chamber therein on a holder holding the wafer by means of an electrostatic chuck or alternatively on a holder""s wafer bearing side having a surface increased in precision so that the wafer can be placed still on and in close contact with the holder and the holder thus heats the wafer directly to heat the wafer uniformly. As such the holder needs to at least have a portion in contact with a wafer that is formed of a material resistant to a highly corrosive gas such as halogen gas and highly heat-conducting, and the holder per se also needs to function to electrostatically chuck, mechanically fix and heat a wafer.
A material having been noted as a material used for forming the holder is aluminum nitride, which is resistant to corrosion and highly heat-conducting. Powdery aluminum nitride is molded to provide media formed thereof and therebetween a coil or wire of a refractory metal such as Mo is interposed and they are then hot-pressed and thus sintered to embed a conductive layer used for a heater, an electrostatic chuck or the like. For example, Japanese Patent Publication No. 2604944 discloses a configuration with an embedded heater allowing a heat emitting side to provide more uniform heat. To provide a conductive layer, a molded medium formed of aluminum nitride and having a surface printed with a paste containing W, Mo or the like is placed on another medium and the aluminum nitride is sintered to provide a holder having a conductive layer embedded therein.
With a holder having such a structure as above, a heater or an electrostatic chuck is powered, as described with reference to FIG. 19. More specifically, as in a holder 110, a ceramic base member 104 has a back side provided with a pipe bonded thereto and accommodating therein extraction lines 107A and 107 B externally feeding power to each of conductive layers 101 and 102 serving as the heater or the electrostatic chuck.
The structure as shown in FIG. 19, however, is inevitably of three dimensions as holder 110 has a back side with pipe 106 bonded thereto. As such, the holder in the form of a disc and pipe 106 for accommodating the extraction lines must be manufactured separately and to bond holder 110 and pipe 106 together a bonding glass must be initially applied and diffusion-bonding or the like must be then employed, which is a cumbersome process.
Furthermore, holder 110 having a back side with a pipe bonded thereto would have front and back surfaces having different levels of heat dissipation. Thus the front side and the back side would have therebetween a difference in temperature and holder 110 would thus distort when it is heated or cooled. While a wafer is placed on holder 110 in close contact therewith so that the wafer is heated with an increased heat-transfer efficiency, holder 110 distorted would provide a gap between the holder and the wafer. This would result in uneven heat transfer which would then cause a variation in the temperature of the wafer""s surface and hence an uneven etch rate and an uneven deposition rate in the wafer""s plane. Accordingly, to prevent the holder from warpage the holder should be formed of a plate at least 5 mm thick, which would increase the cost for its source material(s).
Furthermore, bonding pipe 106 would increase the thermal capacity and if holder 110 is adapted to also function as a heater then it would require a long period of time to heat and cool the holder. Furthermore, in fabricating the pipe when the pipe molded has a binder heated and thus removed therefrom the binder is hard to remove and the pipe can thus break and the pipe tends to be unevenly sintered or deform when it is sintered so that the binder should be removed over a long period of time and furthermore the sintering charge level reduces, which significantly increases the production cost.
Furthermore this structure entails joining at an end of pipe 106. As such, the area for the joint should be considered to maintain the anti-leakage level as required and pipe 106 is thus required to have an increased diameter. Furthermore, if pipe 106 is also required to support holder 110, pipe 106 is also forced to have an increased diameter, resulting in the same disadvantage as described above.
It is possible to widen only the pipe 106 end in the form of a flange. This approach, however, requires applying extraction-molding to extract pipe 106 of a larger diameter and then remove the portion other than the flange.
Furthermore, the structure with pipe 106 joined would be damaged when it is transported, and it also has an in-furnace charge level inevitably reduced when the pipe is joined. Thus the production cost would be increased.
The present invention contemplates a wafer holder for use with a semiconductor manufacturing apparatus that can reduce such distortion as caused when it is heated and cooled and that can also be readily manufactured, and a semiconductor manufacturing apparatus employing the same.
The present invention in one aspect provides a wafer holder for use with a semiconductor manufacturing apparatus, including a conductive layer and a pair of ceramic base members sandwiching the conductive layer therebetween, wherein the conductive layer has a body located at a surface opposite a wafer holding surface of one of the ceramic base members and an extension protruding radially from the body to the outside of a vacuum chamber for external electrical connection, and the body and the extension are arranged substantially in a single plane. Throughout this specification, the extension is also referred to as an xe2x80x9cextractionxe2x80x9d.
Since the present invention in one aspect provides a wafer holder for a semiconductor manufacturing apparatus including a conductive layer having a body and an extension or extraction provided in a single plane, the body and the extraction can be both posed and thus protected between paired ceramic base members each in the form of a flat plate. This can eliminate the necessity of using a pipe for protecting the extraction, as conventional, and hence the necessity of providing the step of bonding the pipe. As such, the wafer holder can be readily manufactured and also free of such distortion as attributed to bonding such pipe.
In the above one aspect the wafer holder preferably includes the ceramic base member formed of at least one material selected from the group consisting of aluminum nitride, silicon nitride, aluminum nitride oxide and aluminum oxide.
As such, a material resistant to corrosion and having a high heat conductance can be appropriately selected as the ceramic base member.
In the above one aspect the wafer holder preferably includes the ceramic base members having a heat conductance of no less than 100 W/mK.
As such, the wafer holder can be improved in heat uniformity to process a wafer more rapidly.
In the above one aspect the wafer holder preferably includes the conductive layer and the ceramic base member with an intermediate layer posed therebetween and formed of a material including at least one of glass having a thermal expansion coefficient of at least 3xc3x9710xe2x88x926/xc2x0C. and at most 8xc3x9710xe2x88x926/xc2x0C. and nonoxide ceramic having a thermal expansion coefficient of at least 3xc3x9710xe2x88x926/xc2x0C. and at most 6xc3x9710xe2x88x926/xc2x0C.
As such, there can be prevented such distortion as attributed to the difference between the thermal expansion coefficient of the intermediate layer and that of the ceramic base member. Furthermore, the thermal expansion coefficient ranged as above can satisfy the requirement that the wafer holder should be heated from a room temperature to 600xc2x0 C. within 30 minutes. Furthermore, the intermediate layer containing nonoxide ceramic allows the wafer holder heated to a high temperature and receiving a high level of voltage to be satisfactorily resistant to heat, corrosion and voltage.
In the above one aspect the wafer holder preferably has the intermediate layer containing nonoxide ceramic containing at least 50% by mass of aluminum nitride or silicon nitride.
The nonoxide ceramic corresponding to aluminum nitride or silicon nitride allows the wafer holder heated to a high temperature and receiving a high level of voltage to be further satisfactorily resistant to heat, corrosion and voltage.
In the above one aspect the wafer holder preferably has the intermediate layer formed of a material including an oxide containing ytterbium, neodymium and calcium or a compound producing an oxide containing ytterbium, neodymium and calcium when heat treatment is performed.
As such, if the base member is formed of aluminum nitride the intermediate layer can have a satisfactory wettability and bond performance.
In the above one aspect the wafer holder preferably has the intermediate layer formed of a material containing an oxide containing yttrium and aluminum or a compound producing an oxide containing yttrium and aluminum when heat treatment is performed.
As such, if the base member is formed of silicon nitride the intermediate layer can have a satisfactory wettability and bond performance.
In the above one aspect the wafer holder preferably includes the ceramic base member having a hole formed therein for arranging a temperature detection unit therein.
Thus the temperature of a surface of a wafer to be processed can be detected by the temperature detection unit. The hole, elongate to introduce the temperature detection unit from the side plate portion into the body to reach a predetermined position, can be readily formed by providing one or both of the substrates with a groove and then bonding them together.
In the above one aspect the wafer holder preferably includes the pair rap of ceramic base members having their respective wafer holding portions sandwiching the body and their respective side plate portions each extending from a side surface of the wafer holding portion and together sandwiching the extraction, and having a width smaller than a width of the wafer holding portion.
As such the heat of the wafer holding portion can be prevented from dissipating to the side plate portion. As such, the wafer holding portion can be rapidly heated to process a wafer more rapidly.
In the above one aspect the wafer holder preferably includes the conductive layer at least having the body formed of a material formed of at least one element selected from the group consisting of W, Mo, Ag, Pd, Pt, Ni and Cr.
Thus the conductive layer can be formed of a material appropriately selected suitable for the production.
In the above one aspect the wafer holder preferably includes the conductive layer corresponding to any one of a heater, an electrode for generating a plasma and an electrode for an electrostatic chuck.
As such, in either one of the heater, the electrode for generating a plasma and the electrode for an electrostatic chuck no pipe is required in protecting an extraction.
In the above one aspect the wafer holder preferably has a total thickness of no more than 5 mm.
As such the wafer holder can heat and cool and thus process a wafer rapidly.
In the above one aspect the wafer holder preferably includes the conductive layer formed of a wire.
As such the present invention can also be applied to a wafer holder including a conductive layer formed of a wire.
In the above one aspect the wafer holder is preferably provided with an O-ring arranged on and extending around the side plate portions of the pair of ceramic base members sandwiching the extraction.
As such, in the semiconductor manufacturing apparatus with the holder attached therein the vacuum chamber can maintain its internal vacuum.
In the above one aspect the wafer holder is preferably provided with a heat insulating neck provided in at least one of the side plate portions of the pair of ceramic base members sandwiching the extraction.
As such, the side plate portion can effectively insulate heat to prevent heat from dissipating from the wafer holding portion to the side plate portion. As such, the wafer holding portion can be improved in heat uniformity, the O ring attached to the side plate portion can be free of thermal degradation, and the side plate portion can be reduced in length.
In the above one aspect the wafer holder is preferably provided with the heater having its body in a region sandwiched between the side plate portions of the pair of ceramic base members.
As such, the side plate portion, readily allowing heat to dissipate, can also emit heat to prevent the side plate portion and therearound from being cooled.
The present invention in one aspect provides a semiconductor manufacturing apparatus having incorporated therein the above wafer holder for use with a semiconductor manufacturing apparatus.
As such, there can be provided a semiconductor manufacturing apparatus having a wafer holder for use with a semiconductor manufacturing apparatus that can be prevented from distorting when it is heated and cooled and that can also be readily manufactured.
In the above one aspect the semiconductor manufacturing apparatus is preferably either one of an etching apparatus, a chemical vapor deposition apparatus and a plasma chemical vapor deposition apparatus.
As such, there can be provided an etching apparatus, a CVD apparatus and a plasma CVD apparatus having a wafer holder for use with a semiconductor manufacturing apparatus that can be prevented from distorting when it is heated and cooled and that can also be readily manufactured.
The present invention in another aspect provides a wafer holder for a semiconductor manufacturing apparatus, including a ceramic base member, a conductive layer provided on the ceramic base member and a protection layer covering the conductive layer, wherein the conductive layer has a body facing a wafer holding surface of the ceramic base member and an extraction extracted from the body for external connection and the body and the extraction are arranged substantially in a single plane.
Since the present invention in one aspect provides a wafer holder for use with a semiconductor manufacturing apparatus including a conductive layer having a body and an extraction provided in a single plane, covering with the protection layer can protect the conductive layer. This can eliminate the necessity of using a pipe for protecting the extraction, as conventional, and hence the necessity of providing the step of bonding the pipe. As such, the wafer holder can be readily manufactured and also free of such distortion as attributed to bonding such pipe.
In the above one aspect the wafer holder preferably includes the ceramic base member formed of at least one material selected from the group consisting of aluminum nitride, silicon nitride, aluminum nitride oxide and aluminum oxide.
As such, a material resistant to corrosion and having a high heat conductance can be appropriately selected as the ceramic base member.
In the above one aspect the wafer holder preferably includes the ceramic base member having a heat conductance of no less than 100 W/mK.
As such, the wafer holder can be improved in heat uniformity to process a wafer more rapidly.
In the above one aspect the wafer holder preferably includes the protection layer formed of a material including at least one of glass having a thermal expansion coefficient of at least 3xc3x9710xe2x88x926/xc2x0C. and at most 8xc3x9710xe2x88x926/xc2x0C. and nonoxide ceramic having a thermal expansion coefficient of at least 3xc3x9710xe2x88x926/xc2x0C. and at most 6xc3x9710xe2x88x926/xc2x0C.
As such, there can be prevented such distortion as attributed to the difference between the thermal expansion coefficient of the protection layer and that of the ceramic base member. Furthermore, the thermal expansion coefficient ranged as above can satisfy the requirement that the wafer holder should be heated from a room temperature to 600xc2x0 C. within 30 minutes. Furthermore, the protection layer containing nonoxide ceramic allows the wafer holder having a high temperature and receiving a high level of voltage to be satisfactorily resistant to heat, corrosion and voltage.
In the above one aspect the wafer holder preferably has the protection layer containing nonoxide ceramic containing at least 50% by mass of aluminum nitride or silicon nitride.
The nonoxide ceramic corresponding to aluminum nitride or silicon nitride allows the wafer holder having a high temperature and receiving a high level of voltage to be further satisfactorily resistant to heat, corrosion and voltage.
In the above one aspect the wafer holder preferably has the protection layer formed of a material including an oxide containing ytterbium, neodymium and calcium or a compound producing an oxide containing ytterbium, neodymium and calcium when heat treatment is performed.
As such, if the base member is formed of aluminum nitride the protection layer can have a satisfactory wettability and bond performance.
In the above one aspect the wafer holder preferably has the protection layer formed of a material containing an oxide containing yttrium and aluminum or a compound producing an oxide containing yttrium and aluminum when heat treatment is performed.
As such, if the base member is formed of silicon nitride the intermediate layer can have a satisfactory wettability and bond performance.
In the above one aspect the wafer holder preferably includes the ceramic base member having a hole formed therein for arranging a temperature detection unit therein.
Thus the temperature of a surface of a wafer to be processed can be detected by the temperature detection unit. The hole, elongate to introduce the temperature detection unit from the side plate portion into the body to reach a predetermined position, can be readily formed by providing one or both of the substrates with a groove and then bonding them together.
In the above one aspect the wafer holder preferably includes the conductive layer at least having the body formed of a material formed of at least one element selected from the group consisting of W, Mo, Ag, Pd, Pt, Ni and Cr.
Thus the conductive layer can be formed of a material appropriately selected suitable for the production.
In the above one aspect the wafer holder preferably includes the conductive layer corresponding to any one of a heater, an electrode for generating a plasma and an electrode for an electrostatic chuck.
As such, in either one of the heater, the electrode for generating a plasma and the electrode for an electrostatic chuck no pipe is required in protecting an extraction.
In the above one aspect the wafer holder preferably has a total thickness of no more than 5 mm.
As such the wafer holder can heat and cool and thus process a wafer rapidly.
In the above one aspect the wafer holder preferably includes the conductive layer formed of a wire.
As such the present invention can also be applied to a wafer holder including a conductive layer formed of a wire.
In the above one aspect the wafer holder preferably includes the ceramic base member and the protection layer having their respective wafer holding portions sandwiching the body and their respective side plate portions each extending from a side surface of the wafer holding portion, together sandwiching the extraction and having a width smaller than a width of the wafer holding portion.
As such the heat of the wafer holding portion can be prevented from dissipating to the side plate portion. As such, the wafer holding portion can be rapidly heated to process a wafer more rapidly.
In the above one aspect the wafer holder is preferably provided with an O ring arranged on the side plate portion of the ceramic base member and the side plate portion of the protection layer together sandwiching the extraction.
As such, in the semiconductor manufacturing apparatus with the holder attached therein the vacuum chamber can maintain its internal vacuum.
In the above one aspect the wafer holder is preferably provided with a heat insulating neck provided in at least one of the side plate portion of the ceramic base member and the side plate portion of the protection layer together sandwiching the extraction.
As such, the side plate portion can effectively insulate heat to prevent heat from dissipating from the wafer holding portion to the side plate portion. As such, the wafer holding portion can be improved in heat uniformity, the O ring attached to the side plate portion can be free of thermal degradation, and the side plate portion can be reduced in length.
In the above one aspect the wafer holder is preferably provided with the heater having its body in a region sandwiched between the side plate portion of the ceramic base member and the side plate portion of the protection layer.
As such, the side plate portion, readily allowing heat to dissipate, can also emit heat to prevent the side plate portion and therearound from being cooled.
The present invention in one aspect provides a semiconductor manufacturing apparatus having incorporated therein the above wafer holder for use with a semiconductor manufacturing apparatus.
As such, there can be provided a semiconductor manufacturing apparatus having a wafer holder for use with a semiconductor manufacturing apparatus that can be prevented from distorting when it is heated and cooled and that can also be readily manufactured.
In the above one aspect the semiconductor manufacturing apparatus is preferably either one of an etching apparatus, a chemical vapor deposition apparatus and a plasma chemical vapor deposition apparatus.
As such, there can be provided an etching apparatus, a CVD apparatus and a plasma CVD apparatus having a wafer holder for use with a semiconductor manufacturing apparatus that can be prevented from distorting when it is heated and cooled and that can also be readily manufactured.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.